Waterjet Cutting

[Phil H 1Participant @philh1]

Having just read an interesting article in the sample Model Engineer, I am interested to know if anybody else has any experience of waterjet cutting services. I am particularly interested in the estimated cutting cost per inch and the ability to drill small holes (say 1/16" or even 3/64" diameter rivet holes). I have messaged one company but was interested to hear from other modellers.

Phil H

[Phil H 1Participant @philh1]

[KWILParticipant @kwil]

I have used SCISS, they have model engineering interests and are very helpful. I am told that the latest lasers are quicker and cheaper and cleaner.

[Phil H 1Participant @philh1]

Ahh so has the laser fought back? I saw samples of both water jet and laser cutting last night at the local ME club. I have no doubt that the water jet was far superior from the samples that I saw but maybe it has changed?

I sent a mail to SCISS and I have received a very good response that has helped me to understand the economics i.e., the need to slow down at corners and pause at the start of cut outs etc etc.

Phil H

[chris jParticipant @chrisj]

Posted by Phil H 1 on 21/09/2012 19:32:22:

Ahh so has the laser fought back? I saw samples of both water jet and laser cutting last night at the local ME club. I have no doubt that the water jet was far superior from the samples that I saw but maybe it has changed?

I sent a mail to SCISS and I have received a very good response that has helped me to understand the economics i.e., the need to slow down at corners and pause at the start of cut outs etc etc.

Phil H

 

Phil

Spread the love

What did you find out about the economics ?

 

Can I ask what magazine edidion you were refering to pls.

Edited By chris j on 21/09/2012 20:05:51

[Phil H 1Participant @philh1]

Chris,

I think I am still in the learning process so there isn't much to say yet. I'd originally asked about something like a £/m or £/inch estimate. I was told that it wasn't so simple because the jet slows down for corners to maintain a true cut without 'flair' and there are stops and starts when piercing holes or cut outs all of which adds time.

The company suggested that I send a drawing, preferably in a Cad .dxf format to receive an estimate. I will be sending some carefully selected examples that help to get closer to my original question.

My thought so far is that the main benefit is probably from the profiling steps e.g., cutting out of the 1/8" steel frames for a locomotive but maybe use traditional, simple drilling jigs for say main horn rivet holes etc…. i.e., steps to help avoid hacksaws and files or a larger milling machine. I also think there might be a benefit from cutting smaller bits such as valve and brake gear.

The article can be seen in the sample electronic model engineer magazine dated 30th May 2003.

Phil H

[chris stephensParticipant @chrisstephens63393]

Hi Guys,

There now seems to be an alternative to Laser and Water jet, and it should be quite considerably cheaper to use, and that is a Plasma Cam. The link below is their demo.

**LINK**

If you like their demo, put PlasmaCam into Youtube and look at Keith Fenner's videos. You might also like this one;

**LINK**

showing what Water Jet can now do. If you were thinking of buying one, wait till after the double rollover, because I suspect only lotto winners could afford one!

chriStephens

[Diane CarneyModerator @dianecarney30678]

There is a firm in the Wrexham area offers waterjet cutting. From conversations I have had the charges are usually per hour but the amount you can get done in an hour makes it definitely worth consideirng.

If anyone remembers the display of three Darjeeling locomotives at various stages of completion at the Harrogate Exhibition, 2011, you may recall that there were a number of waterjet cut items also on display. Much of the work in the locos had been waterjet cut. It was Milner Engineering displaying the locos and they are in a partnership with the waterjet firm so they would be a good first contact. They also do a lot of very heavy work for preserved railways.

From what I have seen, waterjet leaves the cut edge just about as perfect as you could ever get, definitely better than laser cut.

[John Stevenson 1Participant @johnstevenson1]

Chris,

I have a couple of plasma cutters, hand held jobbies. One is a large Cebora that can cut 16mm plate and sever 20mm but it's very heavy to run, I reckon I can get more heat off the gimbal of the electric meter than the torch ! , but it's good.

To that effect I recently bought one f these cheap Cut 40 inverter plasma that run off a three pin plug.

Will cut 6mm and sever 8mm but they really come into thier own around 3mm and "if" the torch control is good enough the finish is equal to laser.

Couple of weeks ago i had some 10" circles to cut out of the front of some control panels, I useually do it with a jig saw and clean up afterwards, a fiddly job.

As an experiment I bolted a lump of angleto the bed of the CNC mill sticking out 3 foot from one end, a simple clamp for the torch was made and a push button replace the button on the torch, simple job as it's got it's own lead.

Then programmed a circle at 10 1/8" to allow for cut off set, started just inside and did a lead in, lead out and the cut was absolutely perfect, just a bit of dross to chip off the underside.

Definitely a method to use for other jobs as it was so simple to impliment and use. I used a 25 gallon drum as the cutting table which is ideal given the hight of the mill.

John S.

[KWILParticipant @kwil]

At the Southern Sub Contractors show held at FIVE (Farnborough) I saw laser cut items you could not tell were laser items, clean square edges without any sign of burning etc.

Edited By KWIL on 22/09/2012 11:02:18

[John Stevenson 1Participant @johnstevenson1]

Just had these cut two weeks ago.

 

 

Starter ring gear for a big vintage stationary engine made with no starter gear, that is a 1 metre rule BTW.

Cut from three 8mm thick plates to keep an accurate tooth profile.

 

 

Close up of the teeth, 185 teeth in 8DP, straight off the laser, no cleanup done at all.

Total cost for these three rings was £142 which was less than getting a blank cut and gearcutting, not including the blank machining

 

John S.

 

[edit] This keyboard kant spel. ]

Edited By John Stevenson on 22/09/2012 13:46:27

[chris stephensParticipant @chrisstephens63393]

Hi John,

That's the way to go. Is there any draft on the teeth?

We had some special chain wheels made and the degree or two of draft had to be machined away to allow the chain to fit! The second batch were better, as they allowed for it, which saved having to mill 60 teeth with a 1/8" end mill. To be fair to the people who did it, I am not sure if they were lasered or watered.

chriStephens

[Phil H 1Participant @philh1]

John,

Those gears look superb and the cost sounds good too. Anybody else got some samples?

Chris, the article I referred to in my opening post suggests a 2 degree draft. Im thinking of locomotive frame profiles so 2 degrees on a 1/8" plate won't really show.

Phil H

[John Stevenson 1Participant @johnstevenson1]

I have loads of stuff cut but it's usually in thicker materials 6, 8, and 10mm usually.

I'll have a look tomorrow and sort out some samples, I don't mind sharing costs but I do get decent rates based on quantity. Often the thinner parts I have done in alloy, ali cuts nice under 3mm.

[Bill PudneyParticipant @billpudney37759]

When I was working we used to get some bulk metal removal done by water jet, generally leaving enough for finish machining. If the requirement was for a higher degree of accuracy the choice was laser cutting, where frequently no subsequent machining was required.

cheers

Bill

[Phil H 1Participant @philh1]

John,

Thats great regarding the prices. I am simply interested in rough estimates at the moment for two reasons as follows;

1. My milling machine is rather small (a small Chester machine). One consideration is to sell it on and get one of its big brothers capable of milling frames quite easily.

2. I have worked out (over the past 2 years) how much free time I have and it is limited. My understanding is that waterjet cutting is capable of quite accurate results and could be used to cut time for parts such as brake hangers and valve gear etc.

Bill,

I am told that the accuracy of water is about 0.1mm with a 2 degree draft. I suspect this is accurate enough for main locomotive frames. Would you agree or do you have reservations? Also, as I suggest above… if I am considering parts such as brake hangers and valve gear – will multiple parts turn out reasonably accurate but more critically the same size when using the same electronic file.

Phil H

[Bill PudneyParticipant @billpudney37759]

I don't want to upset anyone, but I wouldn't know a phoo-phoo valve from a floggle-toggle, locomotives aren't my thing. Still appreciate them though.

However if you are considering cutting profiles, out of up to 3 or 4mm sheet steel then if they can achieve +/-0.1mm, I would think that watercutting would be fine. Nothing that you couldn't tiddly up with a file, 'cos the finish is (or should be) very good. If they can put pilot holes in for the various bolt holes then that's a bonus. The "draft" isn't really a draft angle as understood in casting, it's where the water jet spreads as it goes through the depth of cut. Its why water jet (and laser come to that) are better for thinner materials.

By the way a tolerance of +/-0.1mm, is pretty close to +/-0.004" which used to be the standard tolerance on the lofting plates that we cut on a band saw and filed by hand. Some of them were 96" long without a straight line anywhere. The job time was calculated as total length to be cut and filed, plus an allowance for the number of drill bushes to be inserted.

cheers

Bill

[John Stevenson 1Participant @johnstevenson1]

Another thing to consider is that laser cutting leaves a HAZ [ heat affected zone ] that hardens the surface. Fine like those gear teeth, in fact a bonus but hard on any finishing process unless you get under the HAZ.

Water jet cutting does not suffer from this.

So this could affect the process used depending on tolerances needed.

John S.

[Tony JeffreeParticipant @tonyjeffree56510]

… But of course, water jet cuts with a slight draft.

Regards,

Tony

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